Spectral Addressability in a Modular Two Qubit System.

Area of Science:

• Quantum Information Science
• Synthetic Chemistry
• Molecular Magnetism

Background:

• Synthetic chemistry offers precise control for creating molecular qubits.
• Understanding factors influencing qubit coherence is crucial for quantum information science (QIS).
• The impact of spin-spin distance on electronic spin coherence in molecular qubits requires investigation.

Purpose of the Study:

• To investigate how the distance between two qubits affects electronic spin coherence.
• To design and synthesize molecules with spectrally distinct qubits (Ti³⁺ and Cu²⁺) at varying separations.
• To compare bimetallic species with monometallic controls to isolate effects.

Main Methods:

• Design and synthesis of bimetallic molecules containing Ti³⁺ and Cu²⁺ qubits with controlled metal-metal distances (1.2-2.5 nm).
• Synthesis of monometallic Ti³⁺ and Cu²⁺ complexes as control samples.
• Spectroscopic analysis to probe individual qubits and measure electron spin coherence times.

Main Results:

• Electron spins of one qubit negligibly affect the coherence times of the other, attributed to distinct resonance frequencies.
• Coherence times are primarily determined by the proximity of nuclear spins on the ligand framework of the opposing qubit.
• No significant impact of spin-spin distance on coherence was observed within the studied range.

Conclusions:

• Spectrally distinct molecular qubits minimize interference between qubits.
• Nuclear spin interactions, not direct spin-spin coupling, are the dominant decoherence pathway for these systems.
• Findings provide crucial design principles for developing robust, spectrally addressable molecular qubits for QIS.